Hydraulic governor valve assembly

ABSTRACT

A hydraulic governor valve assembly for hydraulic control system of automatic transmission for vehicles provides low governor pressure at low vehicle speed range, stepwise or steeply increasing pressure at predetermined speed range and then rather gradually increasing governor pressure over the speed range to output circuit, and utilizes the governed pressure as pilot pressure while the low speed range.

United States Patent Ichimura Sept. 12, 1972 [54] HYDRAULIC GOVERNORVALVE 3,048,184 8/1962 Duffy ..137/54 ASSEMBLY 3,279,486 10/1966 Duffy..137/54 3 322 133 5/1967 Searles ..137/56 h I h Y [72] Inventor 25: cokohdm 3,431,928 3/1969 Pierce ..137/54 3,566,894 3/1971 Satoh ..137/541 Asslgnw Nlssan Jldosha Kabushlkl Keisha, 3,568,696 3/1971 Kubo 137/54Yokohama,.lapan 22 Filed; 2 1 70 Primary ExaminerRobert G. NilsonAttorney-Sughrue, Rothwell, Mion, Zinn & Macpeak [21] Appl. No.: 102,151

Related us. Application'Data [571 ABSTRACT [63] Continuation of Ser. No.781,803, Dec. A hydraulic 8 valve p y for hydreulic 1968, abandonedcontrol system of automatic transmission for vehicles provides lowgovernor pressure at low vehicle speed [52] US. Cl ..137/54 rangeStepwise p y increasing Pressure at [51} Int. Cl. ..G05d 13/36predetermined speed rang and th n rather gradually [58] Field of Search..137/54, 56 increasing governor Pressure Over the speed range to outputcircuit, and utilizes the governed pressure as [56] References Citedpilot pressure while the low speed range.

UNITED STATES PATENTS 4 Claims, 4 Drawiiig Figures 2,711,749 6/1955Hettinger ..137/56 PAIENTEBsEP 12 m2 sum 3 or 3 PRESSURE GOVERNOR RPMwm3mmmmm Fig. 4

GOVERNOR PRESSURE RPM mm3wmmma HYDRAULIC GOVERNOR VALVE ASSEMBLY Thisapplication is in continuation of application Ser. No. 781,803, filedDec. 6, I968, and now abandoned.

: The present invention relates to a hydraulic governor device forhydraulic control system of automatic transmission for vehicles.

In a known three speeds full automatic transmission system .for apassenger car, as one example, actuating range of hydraulic shiftcontrol system may be to 40 km/h to shift from first speed to secondspeed and 30 to 90 km/h to shift from second speed to third speed, inrelation to the vehicle speed and the engine throttle valve opening. Therather wide range of the shift speed depends mainly on the throttleopening which determines the shift point at a given vehicle speed. A l2shift valve operates to perform shifting from the first speed to thesecond speed at generally low speed and a 2-3 shift valve operates fromthe second speed to the third speed at relatively high speed. Thehydraulic urging source of the shift valve is governor pressure which ismodulated and reduced pressure from main line pressure of the hydrauliccontrol system so that the governor pressure will never exceed the linepressure. As the governor pressure generally increases as a quadraticcurve, the v inclination of low speed range is rather gradual comparedto higher speed range, consequently, a governor press'ure' curve whichprovides sufficient pressure-change to urge 1-2 shift valve at low speedrange will soon saturate to line pressure and provides no pressurechange to urge 2-3 shift valve at higher speed range. Then, it ispreferable to impart tow characteristic curves to governor pressurehaving stepwise or steep pressure change at a predetermined vehiclespeed and rather gradual quadrant curve above the speed so thatsufficient pressure differences to urge the [-2 shift valve is providedat the low speed range and to urge the 23 shift valve is provided athigher speed range which is rather steep inclination range of thequadrant curve corresponding to speed change.

On of known governors which has above-mentioned sufiicientcharacteristics utilizes the line pressure as pilot pressure so that thevalve must be manufactured as high pressure leak free resulting in highmanufacturing cost.

It is a primary object of the invention to provide a governor valveassembly to supply sufficient pressure differences both to lower speedrange shift valve and to higher speed range shift valve.

Another object of the present invention is to provide aforesaid governorvalve assembly having simple construction, reduced leakage of hydraulicfluid in operation and improved characteristics.

The governor valve assembly having a line pressure passage, a governorpressure passage and a pilot pressure passage comprises, according tothe invention, a first governor valve disposed between the governorpressure passage and the pilot pressure passage to communicate hydraulicpressure to the pilot pressure passage under a predetermined rotationalspeed and to cut off the communication between the both passages overthe predetermined rotational speed, and a second governor valve disposedbetween the line pressure passage and the governor pressure passage toregulate the line pressure and to communicate the governor pressure as afunction of rotational speed of the valve,

the second governor valve providing a valve spool which is urgedradially inwardly by the pilot pressure through the pilot pressurepassage.

FIG. 1 shows longitudinal partial sectional view of one embodiment of agovernor valve assembly according to the invention,

FIG. 2 shows a sectional view along line Il-II of FIG. 1, and

FIG. 3 and FIG. 4 are two charts showing the speed pressurecharacteristic curves of two embodiments of the governor of FIG. 1.

Referring first to FIG. 1, reference numeral 1 designates a power inputshaft which is driven by an output shaft not shown and is carried byautomatic transmission assembly 2. Secured by a key 3 to the shaft 1, anoil distributor 4 is received in an end portion of the automatictransmission assembly and carries a valve body 5. A first governor valve6 having a spool 7 and a spring 8 urging the spool 7 radially inwardlyis radially slidably disposed in the valve body 5, and the sliding axisof the spool 7 is perpendicular to the axis of the shaft 1. A secondgovernor valve 9 having a spool 10 and a spring 11 urging the spoolradially outwardly is slidably disposed in the valve body 5 at theradially opposite direction of the first governor valve 5, and the axisof the spool 10 coincides to the axis of the spool 7. The other ends ofthe springs 8 and 11 are supported respectively by retainers 12 and 13which are secured to the valve body 5.

A conduit 14 communicating with a passage 15 leads line pressure fluidwhich is regulated in a hydraulic control system not shown to thegovernor assembly and a conduit 16 communicating with a passage 17supplies modulated governor pressure fluid to the hydraulic controlsystem to be utilized as a control fluid representing the vehicle speedat that time.

As shown in FIG. 2 the valve body 5 is secured by means of bolts 18 tothe oil distributor 4.

A passage 21 is provided to lead the line pressure through the passage15 to the second governor valve 9, a passage 22 leads the modulatedgovernor pressure to the passage 17 and to the first governor valve 6,and a passage 23 leads pilot pressure from the first governor valve 6 tothe head portion of the second governor valve 9.

The first governor valve 6 provides a governor pressure port 24communicating with the passage 22, a pilot pressure port 25communicating with the passage 23 and an exhaust port 26 communicatingthrough a passage not shown with a common fluid reservoir not shown. Thespool 7 provides two lands 27 and 28 defining between the lands a groove29 which acts as a communicating passage of fluid flowing from the port24 to the port 25. Diameters of the lands 27 and 28 are determinedaccording to desired characteristics of the governor as will beexplained hereinafter.

The second governor valve 9 provides a line pressure port 30communication with the passage 21, a governor pressure port 31communicating with the passage 22, and an exhaust port 32 communicatingwith the reservoir not shown and a fluid chamber 33 communicating withthe pilot pressure passage 23. The spool 10 provides two lands 34 and 35defining between the land a groove 36 which acts as a passage betweenthe line pressure passage 21 and the governor pressure passage 22. Theland 34 has larger diameter than that of the land 35, and head portionof the land 35 protrudes in the fluid chamber 33 and is urged by thepilot pressure.

Operation of the above explained governor valve assembly according tothe invention is as follows: In the first governor valve 6, aspressurized fluid flows into the groove 29 through the passage 22 andthe governor pressure port 24, a hydraulic pressure acts on the spool 7corresponding to the area difference S between the lands 27 and 28 tourge the spool 7 radially outwardly or inwardly; the force is assumed tobe radially outwardly having plus or minus value corresponding to thedifference between the areas of the lands 27 and 28. When then sum ofthis force and the centrifugal force acting on the spool 7 exceed theinitial urging force of the spring 8, the spool 7 moves outwardly sothat the land 27 nearly closes the port 24 to limit flow rate of thefluid, the fluid flows between the land 28 and the adjacent wall surfaceto the exhaust port 26; thus, the fluid pressure in the groove 29reduces from-the governor pressure in the passage 22. When the sum ofthe hydraulic force in the groove 29 and the centrifugal force reduces,the spring 8 urges the spool 7 radially inwardly and opens the port 24to increase flow rate of the fluid through the passage 22 and closes theport 26 to decrease the leakage to the exhaust port 26. Thus, pilotpressure Pp in the groove 29 maintains equilibrium under the nextequation:

in which:

Pp is pilot pressure in the groove 29 S 1 is area difference between thelands 27 and 28 F c is centrifugal force applied to the spool 7 Fs isurging force of the spring 8 V The characteristic curve of governorpressure is represented in solid line in FIGS. 3 and 4. FIG. 3 showsgovernor pressure when diameter of the land 27 is larger than that ofthe land 28 of the first governor valve 8. FIG. 4 shows governorpressure when diameters of the land 27 and 28'are equal. In both casesas the spring 8 retains the spool 7 at low centrifugal force, governorpressure is supplied to passage 23 directly, so that pilot pressure isOH or 6H. In FIG. 3, at point H governor pressure urges the valve spool7 to partially open exhaust port 26 by the land 28, thus pressuremodulating effect is produced and hydraulic pressure through passage 23is lower than governor pressure. As rotation speed increases exhaustport 26 tends to open by the land 28, so that modulated pressure isdecreased until the land 27 completely covers the governor pressurepassage 22, and passage 23 is connected only to exhaust port 26. Thus,hydraulic pressure through passage 23 is represented HE as shown bydotted line in FIG. 3. As hydraulic pressure acting on the spool 10 ofthe second governor valve 9 decreases rapidly, the governor pressureincreases along line HA in FIG. 3. The inclination of line HA is moresteep than first portion of line AB where passage 23 is connected withexhaust pressure.

In the second governor valve 9, the same pressure regulating function isperformed. The spring 11 urges the spool 10 radially outwardly andhydraulic pressure in the groove 36, i.e., the governor pressure actingon the area difference between the land 34 and 35 urges the spool 10radially inwardly since the diameter of the land 34 is larger than thatof the land 35. When the pilot pressure is zero, the aforementionedequilibrium condition in this case is as follows:

in which:

P is governor pressure in the groove 36,

S is area difference between lands 34 and 35,

Fs is urging force of the spring 1 1,

Fe is centrifugal force acting to the spool 10.

The characteristics curve of the governor pressure P is represented ascurve CAB in FIG. 3.

When the pilot pressure through the passage 23 is applied to the head ofthe spool 10, a radially inwardly urging force is applied to the spool10. Thus the equation is modified as follows:

in which:

P is governor pressure,

S is area difference of lands of the spool 10,

Fs is urging force of the spring 1 1,

Fe is centrifugal force of the spool 10,

Pp is pilot pressure applied to the spool 10,

S is head area of the spool 10.

Thus, as shown by full line in FIG. 3, governor pressure drops at lowspeed range CA or OE, and the output governor pressure is represented asline GHAB corresponding to pilot pressure GHE respectively.

Another governor pressure characteristic curve is shown in FIG. 4. Thegovernor pressure shown in FIG. 4 is obtained as a special case of thefirst governor valve 6, in which the diameters of the lands 27 and 28 ofthe spool 7 are equal. In this case, the first governor valve has nopressure regulating function, so that the pilot pressure applied to thehead of the spool 10 through the passage 23 is governor pressure itself.As the area difference between the lands 27 and 28 is zero, it isevident that no hydraulic pressure contributes to the shifting of thespool 7, so that when the centrifugal force Fs is increased the spool 7shifts radially outwardly against urging force of the spring 8 at apredetermined speed to cut off the pilot pressure passage passage 23from the governor pressure passage 22 and to connect the exhaust port 26to the passage 23. Thus the pilot pressure through the passage 23reduces to zero at speed E in FIG. 4, so that the pilot pressure throughthe passage 23 is represented as line GI-IE in FIG. 4. Thus by properlyselecting the diameter of the land 35 of the spool 10, the governorpressure is represented as line GH'AB in FIG. 4 and is applied to thehydraulic shift control system of the automatic transmission through thepassage 22, the passage 17 and the conduit 16.

Thus, as shown in FIG. 3 and FIG. 4, the governor valve assemblyaccording to the invention provides steep or stepwise pressure change atlow speed range and rather steep change at higher speed range, thusproduces sufficient pressure differences to shift l-2 shift valve and2-3 shift valve respectively at desired speed range.

It will be appreciated that the governor valve assembly according to theinvention has many advantages including as follows:

1. Spool valves 6 and 9 are disposed transversely to the axis of theshaft 1, so that maximum diameter of the rotating parts is reduced, andno counter weight is necessary to balance the forces.

2. The first and second governor valves 6 and 9 are coaxial, and theinsided diameters of the valves can be sequentially reduced from outsideof the first governor valve 6, i.e., downwardly in FIG. 2, so that thevalve body 5 can be integral, and can be machined easily.

3. The pilot pressure is regulated from the governor pressure throughthe passage 22, so that hydraulic pressure in the valve body 5 ispositively reduced and oil leakage problems are greatly reduced comparedto known governor valves utilizing line hydraulic pressure as the pilotpressure.

I claim: 1

1. In a hydraulic governor valve assembly adapted to establish apressure signal as a function of rotational speed of the valve, andincluding a valve body, first and second valve chambers formed in saidvalve body, first and second valve elements disposed respectively insaid first and second valve chambers and adapted for radial shiftingmovement with respect to the axis of rotation of the valve body, a linepressure passage connecting a fluid pressure source with the governorvalve assembly to supply line pressure, a governor pressure passage influid communication with the governor valve assembly to deliver saidpressure signal as governor pressure, an exhaust port, a first biasingmeans adapted to radially inwardly bias said first valve element, and asecond biasing means adapted to radially outwardly bias said secondvalve element; the improvement wherein said second valve chamber is influid communication with said line pressure passage and governorpressure passage, said second valve element being adapted to modulateline pressure to produce governor pressure, a first passage meansfurther communicating governor pressure with said second valve chamberto modulate governor'pressure, said first valve element being insertedin said first passage means to block said first passage means fromgovernor pressure when the rotational speed of the valve is increased,whereby governor pressure is increased substantially stepwise at asubstantially predetermined rotational speed of the valve whilesuppressing the leakage from the governor pressure passage.

2. A governor valve assembly according to claim 1, in which said firstgovernor valve provides a valve spool having two lands to communicatethe governor pressure between the lands, so that the governor pressureis modulated to the pilot pressure by the area difference between thelands.

3. A governor valve assembly according to claim 1, in which said firstgovernor valve provides a valve spool having two lands of equal diameterto communicate the governor pressure between the lands, so that thegovernor pressure is not modulated and applied to said second governorvalve as the pilot pressure.

4. In a hydraulic governor valve assembly adapted to establish apressure signal as a function of rotational speed of the valve, andincluding a valve body, first and second valve chambers formed in saidvalve body, first nd second valve eleme ts dis osed res ectivel in s idrm and second valve cliambe i's and a apted fri r rad ial shiftingmovement with respect to the axis of rotation of the valve body, a linepressure passage connecting a fluid pressure source with the governorvalve assembly to supply line pressure, a governor pressure passage influid communication with the governor valve assembly to deliver saidpressure signal as governor pressure, and exhaust port, a first biasingmeans adapted to radially inwardly bias said first valve element, and asecond biasing means adapted to radially outwardly bias said secondvalve element; the improvement wherein said second valve chamber is influid communication with said line pressure passage and governorpressure passage, said second valve element being adapted to modulateline pressure to produce governor pressure, said governor pressurepassage is in fluid communication with said first valve chamber, a pilotpressure passage is in fluid communication with said first and secondvalve chambers to effect urging of said second valve element againstsaid second biasing means and centrifugal force and to reduce governorpressure when said pilot pressure passage is in fluid communication witha fluid pressure, at least said first valve element having two lands ofequal diameter to communicate the governor pressure between the lands,so that the governor pressure is not modulated and applied to saidsecond valve chamber as the pilot pressure, said first element beingadapted to connect said governor pressure passage with said pilotpressure passage at relatively low rotational speed of the valve andbeing further adapted to cut off communication between said governorpressure passage and said pilot pressure passage and to connect saidpilot pressure passage with the exhaust port when the rotational speedof the valve is increased, whereby governor pressure is increasedsubstantially stepwise at a substantially predetermined rotational speedof the valve without permitting leakage to occur from the governorpressure circuit.

ONITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 9 vDated September 12 1972 Hirohisa Ichimura Inventor(s) It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected 'as shown below:

On the cover sheet insert:

[30] ForeignApplication Priority Data December 19;, 1967 Japan..80,980/67 Signed and sealed this' 20th day of August 1974.

(SEAL) Attest:

MCCOY M. GIBSON; JR. v C. MARSHALL .DANN Attesting Officer Commissionerof- Patents FQRM P304050 ($59) uscoMM-oc 60376-P69 I ,5. GOVERNMENTPRINTING OFFICE: 1,, 0-"6-33.

1. In a hydraulic governor valve assembly adapted to establish apressure signal as a function of rotational speed of the valve, andincluding a valve body, first and second valve chambers formed in saidvalve body, first and second valve elements disposed respectively insaid first and second valve chambers and adapted for radial shiftingmovement with respect to the axis of rotation of the valve body, a linepressure passage connecting a fluid pressure source with the governorvalve assembly to supply line pressure, a governor pressure passage influid communication with the governor valve assembly to deliver saidpressure signal aS governor pressure, an exhaust port, a first biasingmeans adapted to radially inwardly bias said first valve element, and asecond biasing means adapted to radially outwardly bias said secondvalve element; the improvement wherein said second valve chamber is influid communication with said line pressure passage and governorpressure passage, said second valve element being adapted to modulateline pressure to produce governor pressure, a first passage meansfurther communicating governor pressure with said second valve chamberto modulate governor pressure, said first valve element being insertedin said first passage means to block said first passage means fromgovernor pressure when the rotational speed of the valve is increased,whereby governor pressure is increased substantially stepwise at asubstantially predetermined rotational speed of the valve whilesuppressing the leakage from the governor pressure passage.
 2. Agovernor valve assembly according to claim 1, in which said firstgovernor valve provides a valve spool having two lands to communicatethe governor pressure between the lands, so that the governor pressureis modulated to the pilot pressure by the area difference between thelands.
 3. A governor valve assembly according to claim 1, in which saidfirst governor valve provides a valve spool having two lands of equaldiameter to communicate the governor pressure between the lands, so thatthe governor pressure is not modulated and applied to said secondgovernor valve as the pilot pressure.
 4. In a hydraulic governor valveassembly adapted to establish a pressure signal as a function ofrotational speed of the valve, and including a valve body, first andsecond valve chambers formed in said valve body, first and second valveelements disposed respectively in said first and second valve chambersand adapted for radial shifting movement with respect to the axis ofrotation of the valve body, a line pressure passage connecting a fluidpressure source with the governor valve assembly to supply linepressure, a governor pressure passage in fluid communication with thegovernor valve assembly to deliver said pressure signal as governorpressure, and exhaust port, a first biasing means adapted to radiallyinwardly bias said first valve element, and a second biasing meansadapted to radially outwardly bias said second valve element; theimprovement wherein said second valve chamber is in fluid communicationwith said line pressure passage and governor pressure passage, saidsecond valve element being adapted to modulate line pressure to producegovernor pressure, said governor pressure passage is in fluidcommunication with said first valve chamber, a pilot pressure passage isin fluid communication with said first and second valve chambers toeffect urging of said second valve element against said second biasingmeans and centrifugal force and to reduce governor pressure when saidpilot pressure passage is in fluid communication with a fluid pressure,at least said first valve element having two lands of equal diameter tocommunicate the governor pressure between the lands, so that thegovernor pressure is not modulated and applied to said second valvechamber as the pilot pressure, said first element being adapted toconnect said governor pressure passage with said pilot pressure passageat relatively low rotational speed of the valve and being furtheradapted to cut off communication between said governor pressure passageand said pilot pressure passage and to connect said pilot pressurepassage with the exhaust port when the rotational speed of the valve isincreased, whereby governor pressure is increased substantially stepwiseat a substantially predetermined rotational speed of the valve withoutpermitting leakage to occur from the governor pressure circuit.